Dynamic Changes of Callose in Microsporogenesis and Microgametogenesis of Rice (Oryza sativa L.)

Callose plays an important role in microsporogenesis and pollen development.However,few studies with the emphasis on callose changes have been carried out in rice.Taichung 65 was employed to investigate the dynamic changes of callose in microsporogenesis and microgametogenesis of rice by using techniques of intact fresh anther epifluorescence microscopy,PEG section epifluorescence microscopy,semi-thin section light microscopy,and TEM.It was found that callose appears in microsporangium at the microspore mother cell formation stage.During meiosis,callose deposition in microspore mother cell firstly occurs on the primary cell wall in the central region of the anther locule,and the intact callose wall appears at the meiotic diakenesis I.In microgametogenesis,callose deposits in tapetal cells and begins to accumulate around microspore nucleus at the early microspore stage,callose deposition around microspore nucleus continues through uninucleate microspore stage.At the late microspore stage,the degeneration of the tapetal cell begins,and the thickening of the endothecium cell wall by callose happens.At the early bicellular pollen stage,accumulation of callose in the cytoplasm of the vegetative cell occurs,and the callose wall of the generative cell is formed and then degraded before the third nuclear migration.At the mature pollen stage,certain amount of callose accumulates in cytoplasm of the vegetative cell.These results indicate that callose metabolism is active and very important not only in microsporogenesis but also in microgametogenesis in rice.